Carburetor with fuel shut-off means having a fuel-air ratio adjustment mechanism

ABSTRACT

In a carburetor construction for metering liquid fuel for delivery downstream of the throttle valve to a spark-ignition engine, means are provided for remotely controlling the fuel-toair ratio including a rapidly operative mechanism for shutting off the fuel source during periods when the engine or vehicle is decelerating toward a predetermined minimum speed value.

waited States Patent Fort 51 June 13, 1972 [54] CARBURETOR WITH FUELSHUT-OFF MEANS HAVING A FUEL-AIR RATIO ADJUSTMENT MECHANISM I [72]Inventor: Edward F. Fort, Naperville, Ill.

[73] Assignee: International Harvester Company, Chicago, Ill.

22 Filed: July17, 1970 21 Appl.No.: 55,804

[52] U.S.Cl "123/97 13, 123/119 D, 123/1 19 DB,

26l/DIG. 19 51 Int. Cl .rozu 9/00, F02n 7/12 58 FieldofSearch ..l23/97B,119D, 119 DB; 26l/DlG. 19

[5v6] References Cited UNITED STATES PATENTS 3,447,516 6/1969Bartholomew 123/97 B 2,036,205 4/1936 Ericson ..l23/97 B PrimaryExaminer-Wendell E. Burns Attomey-Floyd B. Harman [57] ABSTRACT In acarburetor construction for metering liquid fuel for delivery downstreamof the throttle valve to a spark-ignition engine, means are provided forremotely controlling the fuelto-air ratio including a rapidly operativemechanism for shutting off the fuel source during periods when theengine or vehicle is decelerating toward a predetermined minimum speedvalue.

12 Claims, 4 Drawing Figures 40 70 EN G/NE CARBURETOR WITH FUEL SHUT-OFFMEANS HAVING A FUEL-AIR RATIO ADJUSTMENT MECHANISM BACKGROUND OF THEINVENTION This invention relates to a liquid fuel metering system for aspark-ignition internal combustion engine. More in particular thisinvention relates to a carburetor construction employing a fluidicdevice for'metering liquid fuel for delivery through nozzle meanspositioned downstream of the throttle control valve wherein the systemsingularly is capable of supplying fuel to the engine at a substantiallyconstant fuel-air ratio under normal operating conditions for all loadsimposed upon the engine and yet permit the engine to idle under the-samesystem. However, this invention is principally directed to altering, ina favorable direction, the fuel-air ratio delivered when the engine isunder abnormal operating conditions and is an improvement upon thecarburetor construction described in copending application Ser. No.806,645 filed on Mar. 12, 1969, now US. Pat. No..3,544,082 and assignedto the same assignee herein, reference there to being had.

A striking advantage of the present invention is that when a vehicle isdecelerating with the engine under closed or nearly closed throttlecondition, the 'fuel supply to the engine is completely shut-off butprovision is made for smooth restart automatically without attention ofthe operator. Thus hydrocarbons and products of fuel combustiondischarged into the atmosphere during such decelerating periodsattendant thereto are eliminated with a corresponding fuel consumptionimprovement in efficiency. Further, since combustion during deceleratingperiods'is eliminated the engine functions in a manner similar to an airpump which may effectively be utilized in assisting the braking of thevehicle. This is an important feature because there is a considerabledifference between the braking drag of an engine wherein the fuel supplyis cut-off as compared with the braking drag of an engine wherein fuelis fed to the engine at idling rate for in the latter case there iscombustiontakingplace thus obviously providing some power whichappreciably subtracts from the engines braking drag.

SUMMARY OF THE INVENTION An important object of the present invention isto provide a fuel shut-off mechanism in a carburetor which is effectiveduring periods when the associated engine or vehicle is decelerating orwhen such engine is utilized as a brake upon its load.

Another object of the invention is to provide a fuel shut-off mechanismaccording to the preceding object wherein the device functions to cutoff all fuel supply to the engine automatically when the absolutepressure differential between atmospheric pressure and the pressuredownstream of the throttle valve exceeds a predetermined limit.

Still another object of the invention is to provide a fuel shutoffmechanism according to the preceding objects wherein the device isprecluded from functioning to cut off fuel supply to the engine when thevehicle speed is below a predetermined value.

Yet a further object of the invention is to provide a fuel shut-offmechanism according to the preceding objects wherein the device isexternally adjustable for controlling the fuel-to-air ratio delivered tothe engine during normal and abnormal engine operating conditions.

Still a further object of the invention is to provide a fuel shut-offmechanism according to. the immediate preceding object wherein thedevice is remotely adjustable for controlling the fuel-air ratiodelivered to the engine during normal and abnormal engine operatingconditions.

These and other'desirable objects inherent in and encompassed by theinvention will become more apparent from the ensuing description of apreferred embodiment, the appended claims and the annexed drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side view center sectiontaken through the central portion of a carburetor construction showingthe arrangement of the fuel shut-off mechanism of the present invention;

FIG. 2 is a center sectional view, partly broken away, illustrating arotational speed actuated valve which may optionally be included as acomponent of the fuel shut-off device of FIG. 1;

FIG. 3 is a slightly enlarged sectional view taken on line 3- 3 of FIG.1 showing a detail of the fuel discharge member component of the presentinvention; and

FIG. 4 is a slightly enlarged sectional view taken on line 4- 4 of FIG.1 illustrating a detail of the fluidic device employed in the carburetorconstruction of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1 of thedrawing the fluidic fuel metering system or carburetor utilized as anenvironment for the present invention is indicated generally by thenumeral 10. The carburetor 10 includes an air-flow conduit 11 having itsupper end in communication with the atmosphere, usually through aconventional air filter (not shown), and its lower end in communicationwith the cylinders through an intake manifold, of an internal combustionengine (not shown). Air flowing through the conduit 1 l is controlled bya conventional throttle valve generally indicated at 12 which is variedby a rotational movement of the throttle valve shaft 13 in aconventionalmanner.

The conduit 11 includes a restriction or venturi portion 14 whichreduces the static pressure of air flowing therethrough to createcontrol signal pressures related to the rate of air flow through theconduit 1 l which will be discussed herein more in detail.

The carburetor 10 is provided with a conventional fuel float bowl orfloat chamber indicated generally at 15. The chamber 15 includes a float16 connected to an arm 17 pivotally connected at 18 to a side wall 19 ofthe carburetor 10. The arm 17 is provided with a valve element 20 incooperative alignment with valve seat 21 in a conventional manner. Asource of liquid fuel under pressure above atmospheric is connected topipe 22 whereby liquid fuel isadmitted into the float chamber .15 viaconduit 22 and valve 20,21 until the amount of fuel 23 in the floatchamber 15 reaches a predetermined fuel level 24 as indicated in thedrawing. The upper portion of the float chamber 15 communicates with theupper portion of the inlet air-flow conduit 1 1 through passage 31having a port 32 opening into the conduit 11 as shown in FIG. 1'.

The carburetor 10 is provided with a fluidic device generally indicatedat 25 which includes an interaction zone 26 having a restriction orinlet nozzle 27, as shown in FIGS. 1 and 4, in communicationwith thefloat chamber 15 through fuel passage 28. Thus liquid fuel from thefloat chamber 15 may enter the interaction zone 26 through passage 28and inlet port or nozzle 27.

The carburetor 10 is provided with a liquid fuel discharge memberindicated generally at 29 extending into the air-flow conduit 11 andpositioned below the throttle valve 12. The discharge member 29comprises a tubular element 30 having at least one slit or elongatedorifice 33 preferably disposed at right angle with reference to theinlet air-flow conduit 11 as shown in FIGS. 1 and 3, The dischargemember 29 communicates with interaction zone 26 of the fluidic device 25through outlet port 34 and outlet passage 35. Thus liquid fuel from thefloat chamber 15 is diverted by the nozzle 27 through the interactionzone 26 into port 34 and thereafter conducted to the discharge orifice33 through outlet passage 35 and discharge member 29.

It will be noted that the float chamber 15 is positioned with respect tothe fluidic device 25 whereby the fuel level 24 is maintained at or justslightly below the horizontal plane of the nozzle 27. If the fuel level24 is above the nozzle 27 liquid fuel from the float chamber 15 willdrain into the air-flow conduit 11 during periods when the engine is notoperating which would result in loss of fuel and may affect the abilityof the engine to start easily. On the other hand, the fuel level 24should not be substantially below the horizontal plane of nozzle 27because it would then require an unnecessarily higher pressuredifference to cause the liquid fuel to flow through the nozzle 27.

In the drawing it will be observed that the interaction zone 26 of thefluidic device 25 communicates with air-flow conduit 11 through thesignal port openings 36 disposed preferably at right angle with respectto the inlet air-flow conduit as indicated in FIGS. 1 and 4. Thedistance between the nozzle 27 and the signal port opening 36 ideallyshould be zero. However, practically the distance between the nozzle 27and pressure signal port opening may be as much as about one-half thetotal wetted perimeter of the port opening 36. For example a distance ofabout one-sixteenth inch provides very satisfactory operation. Asindicated in FIG. 1, the signal port opening 36 may conveniently be inthe form of a slit or elongated aperture which communicates theinteraction zone 26 of the fluidic device 25 with the venturi portion 14of the inlet air-flow conduit 1 1. I

For normal operation of the internal combustion engine served by thecarburetor the aggregate cross-sectional area of the orifice 33 in thedischarge member 29 is important and should preferably be from one-halfto three times the crosssectional area of the nozzle 27. However, aswill be apparent later herein, the present invention includes means foradjusting the magnitude of the cross-sectional opening of orifice 33 notonly to obtain the optimum size for normal engine operation but also forabnormal engine operating conditions such as, for example, starting acold engine and subsequent operation thereof until normal enginetemperature is reached.

Referring again to the drawing it will be noted that in the inletair-flow conduit 11 there are three principal signal pressure regionsindicated at X, Y, and Z. The rate of metering of fuel 23 from the floatchamberlS through the fluidic device 25 is a function directly relatedto the composite or integrated effect of the three absolute pressuremagnitudes existing in regions X, Y, and Z during any predeterminedoperating condition of the engine. The absolute pressure at region X hasbeen found to be slightly below atmospheric pressure and varies onlyslightly under all engine operating conditions at any given elevationwith reference to sea level. The absolute pressure in region Y at theventuri portion 14 of the air-flow conduit 11 reaches its lowest valuewhen the throttle 12 is at its maximum open position (i.e. maximumthrottle engine operation) and rises progressively to a maximum valuesomewhat below the absolute pressure value in region X when the throttle12 is nearly closed (i.e. operation of the engine at idling condition).The range of absolute pressure values in region Z has the widestvariation. During operation of the engine at idling condition theabsolute pressure value in region 2 is very low, that is to say apressure value of much lower magnitude than that found in regions X or Yunder any engine operating condition. On the other hand, when thethrottle 12 is at its wide open position (i.e. engine operating at fullload) the absolute pressure value in region Z will be slightly greaterthan the corresponding pressure value in region Y.

In operation, from the above, it will be apparent that under all engineoperating conditions the absolute pressure value in region X will alwaysbe greater than at either region Y or region 2. Therefore the airpressure in the float chamber 15 will drive the liquid fuel 23 throughthe nozzle 27. The nozzle 27 is so positioned that the liquid fuelemanating therefrom is directed toward the outlet port 34 and if thefluidic device is properly arranged all fuel delivered into the conduit11 will preferably be through the orifice 33 of the discharge member 29during any engine operating condition. Otherwise at wide open throttleor near wide open throttle engine operating condition some fuel mayenter the air-flow conduit 11 through the port opening 36. From this itwill be apparent that in general operation no fuel is discharged throughport openings 36 but,

to the contrary some air may enter these ports 36 and mix with the fueldirected through the outlet passage 35 The foregoing describes acarburetor construction providing a suitable environment for theinvention, now to be explained in detail wherein means are provided forremotely controlling the air-fuel ratio including a rapidly operativemechanism for shutting off the fuel source during periods when theengine speed is decelerating under reduced throttle toward apredetermined speed value. The invention may therefore be considered tobe an air-fuel ratio control mechanism capable of regulating thecross-sectional area of the fuel discharge orifice 33 from maximum openposition to closed position, as may be desired, with means forautomatically closing the fuel discharge orifice 33 when the engine orvehicle is decelerating toward a predetermined minimum speed value or,alternatively, during periods when the engine is being driven by themomentum of its load at a speed above its predetermined minimum speedvalue such as that which occurs when a vehicle is moving downhill.

Referring to FIG. 1 it will be seen that the spray bar 30 of the fueldischarge member 29 is a tubular structure having one end incommunication with the outlet passage 35. Disposed in slidable relationwithin the spray bar 30 is a movable plunger 37 which is capable ofbeing moved rightwardly in FIG. 1 to an extreme position, indicated bythe dotted line 38, which closes communication of the outlet passage 35with the discharge orifice 33 and leftwardly to an extreme positionwhere the entire discharge orifice 33 is in opencommunication withoutlet passage 35. Thus, it will be apparent that movement of theplunger 37 correspondingly regulates the flow of fuel from the outletpassage 35 into the inlet air-flow conduit 11 through the variable sizeopening of the discharge orifice 33 thereby correspondingly regulatingthe air-fuel ratio delivered to the engine. Means for controlling theposition of the plunger 37 in respect of the discharge orifice 33 willnow be described.

The air-fuel ratio control mechanism of this invention includes anactuator device generally indicated at 40, which may be integral withthe carburetor 10 as shown in FIG. 1 or constructed as a separatecomponent suitably secured, as by screws, to the casing 41. The plunger37 includes a stem 42 which passes through a hole 43 in the casing 41and projects into a room 44 of the actuator device 40. The room 44 isdivided into a chamber 45 and a compartment 46 hermetically sealed fromeach other by a flexible diaphragm 47. The stem 42 extends through thediaphragm 47, by conventional clamping seal indicated at 48, and abuts abushing assembly indicated at 49. The bushing assembly 49 comprises abushing 50 joumaled for slidable movement through bore 51 in the wall 52of the actuator device 40 as may be evident from FIG. 1. The bushing 50is provided with a cylindrical recess 53 having internal threadstherein. Threadedly fit within the recess 53 is a pin 54 having a head55 forming a cam follower. The leftward end of the bushing 50 may beformed into a hexagonal head 50a suitable for wrench-engaging means.Likewise the head 55 of the pin 54 may be provided with ahexagonal-shaped portion 55a also suitable for wrench-engaging means.Thus it will be apparent that by relative rotational movement betweenthe pin 54 and bushing 50 the distance between the abutment 56 of thebushing 50 relative to the cam follower 55 is adjustable. Suitablelocknuts or other conventional means (not shown) may be employed to lockthe pin 54 from rotational movement with reference to the bushing 50.

A convenient means for engaging the cam follower 55 for adjustablymoving the bushing assembly 49 and its abutment 56 may comprise a cam 57mounted for rotational movement on a shaft 58. A compression spring 59anchored on the casing 41 and seated on the clamping seal 48 urges theplunger 37 and bushing assembly 49 leftwardly as viewed in FIG. 1 sothat the cam follower 55 is urged against the cam lobe 57a. The cam 57is moved rotatively about the axis of its shaft 58 either by applyingsufficient torque to the shaft 58 or by appropriate movement remotely oflever 60 connected to the cam 57. Thus it will be apparent that byproper selection of the curvature of cam lobe 57a the position of theplunger 37 with reference to the elongated orifice 33 variescorrespondingly the size of the opening 33 for discharging fuel into theinlet air-flow conduit. From this it will be apparent that the air-fuelratio may be selectively altered such as for starting and operating acold engine or changing the air-fuel ratio corresponding to variationsin atmospheric pressure such as that which oc curs by reason of changesin altitude.

From the foregoing it will be seen that the bushing assembly 49 and itsassociated cam 57 provides an operative adjustable stop means forlimiting the leftward movement of the plunger 37 as viewed in FIG. 1 andthereby controlling the size of the discharge orifice. It will beobvious to those skilled in the art that an ordinary bolt threadedly fitinto bore 51 could be substituted for the bushing assembly 49 and cam 57thereby providing a stationary abutment 56 thus fixing the maximum sizeof the discharge orifice 33.

Means will now be described for energizing the actuator device 40wherein the plunger 37 is moved rightwardly to its extreme positionwherein the discharge orifice 33 is closed and thus no fuel isdischarged into the inlet air-flow conduit 1 1 from the outlet passage35. Broadly speaking, this entails communicating the inlet air-flowconduit 11 at signal pressure re gion Z (downstream of the throttlevalve 12) with chamber 45 during periods of engine operation when fuelcut-off is desired. 7

The actuator device 40 may be operated by means such as a pressuresensing valve indicated generally at 61 in FIG. 1. The valve'means 61may comprise a valve housing 62 having axially aligned bores 63, 64 and65 as shown in FIG. Disposed in the bore 64 for axial movement thereinis a valve spool in dicated' generally at 66. Valve spool 66 is providedwith lands 67, 68 forming a circumferential groove 69 therebetween.Extending leftwardly from the land 67 the valve spool 66 is providedwith a shoulder 70 which serves to limit the leftward movement of thespool 66. Vent 71 in the valve housing 62 is provided to vent the formedcompartment 72.

Disposed in compartment 73 formed in bore 64 rightwardly of land 68 is acompression spring 74 which urges the valve spool 66 leftwardly to abutthe'shoulder 70 against the valve housing 62 as is evident from FIG. 1.Vent 75 in the valve housing 62 is provided to vent the compartment 73.Port 76 communicates with chamber 45 of actuator device 40 through pipe77. Port 78 in the valve housing 62 is positioned for continuouscommunication with circumferential groove 69 irrespective of the axialposition of the valve spool 66 in the bore 64. i i

In order to actuate axial movement of the valve spool 66 against theurging of spring 74, the valve means 61 includes a cylinder indicated at82. Disposed within the bore 63 of cylinder 82 in slidable relation is apiston 79 having the face 80 thereof exposed to the atmosphere as shownin FIG. 1. Piston 79 includes a piston rod 81 slidably disposed in thebore 65 which rod may be, but not necessarily, integral with shoulder 70of the valve spool 66. The piston 79 in the bore 63 of the housing 62forms a cylinder cavity 83 communicatively connected to port 78 throughpipes 84 and 85. Pipe 85 communicates with signal pressure region 2 ofcarburetor through pipe 86, shut-off valve (in open position) 87, pipes88 and 89 and port 90 positioned in casing 41 downstream of the throttlevalve 12.

In the arrangement just described it will be seen that when the throttlevalve 12 is open to a degree such as that which occurs when the engineis driving a load, the absolute pressure value (i.e. a vacuum) in thecavity 83 of the pressure sensitive valve means 61 will be substantiallyequal to the absolute pressure value of the signal pressure region Z butthe pressure differential then existing between cavity 83 and theatmosphere will be insufficient to move the piston 79 against the urgingof the spring 74.- Thus the valve spool 66 of the valve means 61 willremain in the position shown in FIG. 1 and the chamber 45 of theactuator device 40 is in communication with the atmosphere through pipe77, port 76, compartment 73 and vent 75. Under such operating conditionthe position of the plunger 37 with reference to the discharge orifice33 remains under control through manual (or otherwise) operation of thecam 57.

When the throttle valve 12 is substantially closed, and the engine speedis near that which occurs when the engine is permitted to idle under ano-load idling condition, the absolute pressure in the signal pressureregion Z communicated to the cavity 83 of the valve means 61 reaches arelatively low value. However, this value is still such that atmosphericpressure on the face 80 of the piston 79 will be insufficient to movethe piston 79 such that the land 68 of the valve spool 66 will movetoward port 76. Thus when the engine idles .normally the chamber 45 ofthe actuator device is not yet in communication with signal pressureregion Z and therefore the position of the plunger 37 with reference tothe discharge orifice 33 remains under control through operation of thecam 57. From this it will be apparent that the size of the piston 79 andthe characteristics of the spring 74 should be chosen such that theabsolute pressure value in the signal pressure region Z during normalengine idling is barely high enough so that the valve spool 66 will notmove sufficiently to communicate port 76 with circumferential groove 69.

When the speed of the engine is elevated under no-load or low load andthe throttle 12 is moved into idling position the absolute pressure inthe pressure region Z drops to values below the above described normalvalues because the engine is being driven principally by its ownmomentum or kinetic energy until its speed reduces or approaches idlingspeed. A similar drop in the absolute pressure in the pressure region Zoccurs also when the throttle 12 is moved substantially to idle positionduring periods when the engine is being driven by the kinetic energy ofits load such as that which occurs when an engine driven vehicle ismoving downhill while in gear. Under either of these conditions theresulting absolute pressure value in the pressure region Z being lowerthan the value obtained under normal engine idling or power producingconditions creates a differential pressure between cavity 83 and theatmosphere so that. the piston 79 moves the valve spool 66 rightwardlysuch that port 78 communicates with port 76 through circumferentialgroove 69 thereby communicating the pressure existing in pressure region2 with chamber of the actuator device 40. The drop in pressure withinthe chamber 45 permits atmospheric pressure in compartment 46 throughvent 91 to overcome spring 59 and drive rightwardly the flexiblediaphragm 47, clamping seal assembly 48, stem 42 and plunger 37 to thedotted line 38 thereby closing the discharge orifice 33. Thus all fuelflow is shut off and therefore fuel delivery to the engine isterminated, i.e. zero fuel-air ratio. Under such conditions at leastthree distinct advantages occur. First, since no fuel is delivered tothe engine there can be no combustion and thus the engine functionsentirely as a pump. The engine may thus function much more efficientlyas a speed retarder than when combustion is permitted to take place ifidling air-fuel ratio mixture is delivered to the engine. Second, thereis obviously an improved fuel economy. Third, the shutting off of thefuel flow during such periods of operation serves to minimize unwantedengine emissions into the atmosphere.

During periods when the fuel is shut off as above described any airwhich may have entered into the outlet passage 35 through the apertures36 will rise thus leaving a column of liquid fuel in the passage 35which is immediately available for restarting engine combustion. Enginerestart commences automatically when the engine speed reduces to somepreset value above idling speed at which time the absolute pressure inthe signal pressure region Z rises to the restart pressure value. Whenthe pressure in the signal pressure region Z rises to the restartpressure value then the spring 74 of the pressure sensitive valve meansovercomes the atmospheric pressure acting on the piston .79 permittingthe'chamber 45 to re- 77, port 76, compartment 73 and vent 75. Thus thespring 59 moves the plunger 37 with its associated stem 42 and clampingseal assembly 48 back into abutting relation with abutment 56 of thebushing assembly 49 as shown in FIG. 1. When this occurs the column ofliquid fuel (free of air bubbles) in the outlet passage 35 is availablefor immediate discharge into the inlet air-flow conduit 1 1 through thefuel discharge orifice 33. Since the column of liquid fuel in thepassage 35 is at that time temporarily free of air bubbles the initialrate of fuel flow through discharge orifice results in a, temporarilyenriched airfuel ratio delivered by the carburetor to the engine.

If desired optionally the actuator device 40 may be rendered inoperativeto shut off the fuel flow when the vehicle speed is below apredetermined minimum speed by simply interposing a vehicle speedsensitive valve mechanism, indicated generally at 92 in FIGS. 1 and 2,communicatively connected to pipes 85 and 89 and either closing valve 87or eliminating valve 87 and associated pipes 86 and 88. The speedsensitive valve 92 merely communicates pipe 85 with pipe 89 duringperiods when the speed of the vehicle exceeds a predetermined value thusrendering the actuator device 40 operative and, to the contrary, rendersthe actuator device 40 inoperative when the vehicle speed is at or belowthe aforesaid predetermined value. One form of speed sensitive valvemechanism is illustrated in FIG. 2 which will now be described.

In FIG. 2 the mechanism 92 comprises a stationary hollow housing 93forming a first compartment 94 communicatively connected to signalpressure region Z of the carburetor 10 through pipe 89. Disposed withinthe compartment 94 in journaled relation is a hollow rotor 95 forming asecond compartment 96 therewithin. The rotor 95 is provided with anexternally protruding shaft 97 suitably connected in driven relationwith the vehicle such as from the speedometer cable. The housing 93 isprovided with an internal circumferential groove 98 communicativelyconnected to pipe 85 through port 99. Disposed within the shaft 97 is apassage 100 continuously communicating circumferential groove 98 withthe second compartment 96. Positioned at the periphery of the rotor 95is a poppet valve assembly indicated generally at 101. As shown in FIG.2 the poppet valve 101 is in open position which occurs when the rotor95 is rotating above a predetermined speed value thereby communicatingthe first compartment 94 with the second compartment 96 in which casethe pipe 85 is in communication with the pipe 89. Thus the conditionexists where the valve means 61 and actuator device 40 is renderedoperative as previously described. If the rotational speed of the rotor95 decreases to a predetermined value then the tension spring 102 willovercome the centrifugal force of the valve body 103 and thus the valveassembly 101 will close. When the valve assembly 101 closescommunication between pipe 89 and pipe 85 is terminated. In thiscondition the valve means 61 is rendered inoperative and the actuatordevice 40 cannot function to close the discharge orifice 33 in responseto the absolute pressure existing in the signal pressure region Z. Inorder to prevent the possibility of having the chamber 45 undersub-atmospheric pressure when the poppet valve assembly 101 closes ameans for automatically venting the chamber 45 to the atmosphere undersuch condition will now be described.

Disposed within the shaft 97 is a second passage 104 which is incontinuous communication with a circumferential groove 105 positioned inthe stationary housing 93 as shown in FIG. 2. The circumferential groove105 is in communication with the atmosphere through the port 106. Thesecond passage 104 also communicates with the second compartment 96through port 107. The valve body 103 is provided with a valve element108 positioned such that when the poppet valve assembly 101 is in openposition the valve element 108 closes the port 107 thereby precludingcommunication between the second compartment 96 and the atmosphere whenthe rotational speed of the valve mechanism 92 is above a predeterminedminimum rotational speed value. Under such condition the actuator device40 is operatively connected to function as hereinbefore described.However, when the speed of the vehicle is below a predetermined value,the poppet valve assembly 101 closes thus terminating communicationbetween pipes and 89 and at the same time opens the valve element 108thereby venting the second compartment 96 with the atmosphere throughport 107, second passage 104 and port 106. In the latter condition thechamber 45 is also vented to the atmosphere because the cylinder cavity83 is thereby vented to the atmosphere and the pressure sensitive valvemeans 61 will move to the position shown in FIG. 1 which communicatesthe pipe 77 with the atmosphere through vent 75. Thus when the speed ofthe vehicle is below a predetermined value set by the speed sensitivevalve mechanism 92 the actuator device 40 is deactivated in whichcondition fuel is supplied to the engine in an air-fuel ratio consistentwith the position of the cam 57.

Although the invention has been described in considerable detail withparticular reference to certain proposed embodiments thereof, variationsand modifications may be efiected within the spirit and scope of theinvention as described hereinabove and as defined in the appendedclaims.

What is claimed is:

1. For a spark-ignition internal combustion engine carburetor having anair-fuel conduit and a throttle valve positioned therein, a fuel-to-airratio regulating means, comprising,

a. a fuel discharge member including an elongated, generally tubular barextending normally with respect to the longitudinal axis of saidair-fuel conduit and having fuel discharge orifice means formedtherethrough disposed downstream of said throttle valve providingcommunication between the interior of said tubular bar and said conduitdownstream of said throttle valve, substantially all of the liquid fuelrequired by the engine to said conduit being introduced through saiddischarge orifice means;

b. a movable element associated with said tubular bar and cooperablewith said fuel discharge orifice means, the effective cross sectionalarea of said orifice means being directly dependent upon the position ofsaid movable element with respect to said tubular bar and continuallyvarying in accordance with movement of the movable element with respectto said tubular bar, said movable element being movable between a closedposition wherein communication between the interior of said tubular barand said conduit is precluded and fully open position wherein apre-established effective cross sectional area of said discharge orificemeans affords maximum communication for the flow of liquid fuel betweenthe interior of said tubular bar and said conduit;

0. biasing means yieldably urging said movable element in one directiontoward its fully open position;

d. stop means operatively engageable with said movable element to limitmovement of said movable element in said one direction and therebyestablish the fully open position of said movable element; and

e. actuating means for moving said movable element toward its fullyclosed position against the resilient action of said biasing means, saidactuating means being responsive to the absolute pressure value in saidconduit downstream of said throttle valve and being effective to rapidlymove said movable element to its closed position and to maintain suchclosed position when said absolute pressure value in said conduitdownstream of said throttle valve is below a predetermined value, saidbiasing means being effective to rapidly move said movable element insaid one direction and into operative engagement with said stop meanswhen the absolute pressure value in said conduit downstream of saidthrottle valve rises to a value at least equal to said predeterminedvalue.

2. A fuel-to-air ratio regulating means as set forth in claim 1, whereinsaid discharge orifice means is partially defined by an elongated slitformed through the wall of said tubular bar, the longitudinal axis ofsaid slit being substantially parallel to the longitudinal axis of saidtubular bar, and said movable element includes a plunger mounted withinsaid tubular bar for sliding movement along the longitudinal axis ofsaid tubular bar.

3. A fuel-to-air. regulating'means as set forth in claim 2, wherein saidactuating means includes an actuating device operatively connected tosaid plunger, and passageway means extending and providing communicationbetween said conduit downstream of said throttle valve and saidactuating device, and a speed responsive valve mechanism interposed insaid passageway means, said valve mechanism being responsive to therotational speed of the engine and being effective to disruptcommunication between said conduit downstream of said throttle valve andsaid actuating device only when the rotational speed of the engine is atand below a predetermined rotational speed to thereby rendertheactuating means ineffective to move said movable element toward itsfully closed position against the resilient action of said biasingmeans.

4. A fuel-to-air ratio regulating means'as set forth in claim 3, whereinsaid movable element includes an elongated stem having one end fixed toone end of said plunger, and said stop means includes an abutmentdisposed in the path of movement of said stem, the end of said stemopposite the end fixed to said plunger abutting said abutment when saidmovable element is in its fully open position and therebylimitingmovement of said movable element in said one direction.

5. A fuel-to-air ratio regulating means as set forth in claim 1, furtherincluding manually operable adjustment means for said stop means, saidadjustment means being manually operable to selectively vary thepreestablished effective cross sectional area of said discharge orificemeans affording maximum communication for the flow of liquid fuelbetween the interior x movement of said plunger with respect to saidslit.

8. A fuel-to-air ratio regulating means as set forth in claim ,7,wherein said manually. operable adjustment means includes a rotatablecam having a cam surface formed thereon, and a cam follower operativelyengaging said cam surface and connected to said abutment for cojointmovement along an axis coincident with the movement axis of saidplunger, said cam and cam follower being effective upon rotation of saidcam to vary the position of said abutment along the path of movement ofsaid plunger with respect to said slit.

9. A fuel-to-air ratio regulating means asset forth in claim 8, furtherincluding remote control means for rotating said cam remotely of thecarburetor.

10. A fuel-to-air ratio regulating means as set forth in claim 1,further including a liquid fuel reservoir; passageway means extendingbetween" and' providing fluid communication between said fuel reservoirand said tubular bar; and a fluidic device formed within a section ofsaid passageway means between said fuel reservoir andsaid'tubular bar,said fluidic device being responsive to the absolute pressure magnitudesexisting in certain regions of said conduit spaced along thelongitudinal axis thereof and being effective to control the fuel ofsaid tubular bar and said conduit when said movable element is in itsfully open position.

6. A fuel-to-air ratio regulating means as set forth in claim 5, whereinsaid discharge orifice means is partially defined by an elongated slitformed through the wall of said tubular bar, the

longitudinal axis of said slit being substantially parallel to thelongitudinal axis of said tubular bar, said movable element includes aplunger mounted within said tubular bar for sliding movement along thelongitudinal axis of said tubular bar.

7. A fuel-to-air ratio regulating means as set forth in claim 4, furtherincluding manually operable adjustment means for said stop means, saidadjustment means being operable to selectively vary the position of saidabutment along the path of flow rate through said passageway means.

11. A fuel-to-air ratio regulating means as set forth in claim 10,wherein said air-fuel conduit is formed with a reduceddiameter venturiportion upstream of said throttle valve and said fluidic device isdisposed within said conduit at said venturi portion, said fluidicdevice including a wall section of said passageway means partiallydefining an interaction zone, said fluidic device including a restrictedfuel inlet nozzle providing fluid communication between said fuelreservoir and said interaction zone, a signal pressure port forsubjecting said interaction zone to the absolute pressure magnitudeexisting in said conduit at said venturi portion, and an outlet port;said fuel reservoir being subjected tothe absolute pressure magnitudeexisting in said air-fuel conduit upstream of said venturi portion.

12. A fuel-to-air ratio regulating means as set forth in claim 11,wherein said fluidic device is vertically spaced above said tubular bar,and said passageway means extending between said fluidic device and saidtubular bar being capable of serving as means for storing fuel trappedwhen said movable element is moved to its closed position

1. For a spark-ignition internal combustion engine carburetor having anair-fuel conduit and a throttle valve positioned therein, a fuel-to-airratio regulating means, comprising, a. a fuel discharge member includingan elongated, generally tubular bar extending normally with respect tothe longitudinal axis of said air-fuel conduit and having fuel dischargeorifice means formed therethrough disposed downstream of said tHrottlevalve providing communication between the interior of said tubular barand said conduit downstream of said throttle valve, substantially all ofthe liquid fuel required by the engine to said conduit being introducedthrough said discharge orifice means; b. a movable element associatedwith said tubular bar and cooperable with said fuel discharge orificemeans, the effective cross sectional area of said orifice means beingdirectly dependent upon the position of said movable element withrespect to said tubular bar and continually varying in accordance withmovement of the movable element with respect to said tubular bar, saidmovable element being movable between a closed position whereincommunication between the interior of said tubular bar and said conduitis precluded and fully open position wherein a pre-established effectivecross sectional area of said discharge orifice means affords maximumcommunication for the flow of liquid fuel between the interior of saidtubular bar and said conduit; c. biasing means yieldably urging saidmovable element in one direction toward its fully open position; d. stopmeans operatively engageable with said movable element to limit movementof said movable element in said one direction and thereby establish thefully open position of said movable element; and e. actuating means formoving said movable element toward its fully closed position against theresilient action of said biasing means, said actuating means beingresponsive to the absolute pressure value in said conduit downstream ofsaid throttle valve and being effective to rapidly move said movableelement to its closed position and to maintain such closed position whensaid absolute pressure value in said conduit downstream of said throttlevalve is below a predetermined value, said biasing means being effectiveto rapidly move said movable element in said one direction and intooperative engagement with said stop means when the absolute pressurevalue in said conduit downstream of said throttle valve rises to a valueat least equal to said predetermined value.
 2. A fuel-to-air ratioregulating means as set forth in claim 1, wherein said discharge orificemeans is partially defined by an elongated slit formed through the wallof said tubular bar, the longitudinal axis of said slit beingsubstantially parallel to the longitudinal axis of said tubular bar, andsaid movable element includes a plunger mounted within said tubular barfor sliding movement along the longitudinal axis of said tubular bar. 3.A fuel-to-air regulating means as set forth in claim 2, wherein saidactuating means includes an actuating device operatively connected tosaid plunger, and passageway means extending and providing communicationbetween said conduit downstream of said throttle valve and saidactuating device, and a speed responsive valve mechanism interposed insaid passageway means, said valve mechanism being responsive to therotational speed of the engine and being effective to disruptcommunication between said conduit downstream of said throttle valve andsaid actuating device only when the rotational speed of the engine is atand below a predetermined rotational speed to thereby render theactuating means ineffective to move said movable element toward itsfully closed position against the resilient action of said biasingmeans.
 4. A fuel-to-air ratio regulating means as set forth in claim 3,wherein said movable element includes an elongated stem having one endfixed to one end of said plunger, and said stop means includes anabutment disposed in the path of movement of said stem, the end of saidstem opposite the end fixed to said plunger abutting said abutment whensaid movable element is in its fully open position and thereby limitingmovement of said movable element in said one direction.
 5. A fuel-to-airratio regulating means as set forth in claim 1, further includingmanually operable adjustment means for said stop means, said adjustmentmeans Being manually operable to selectively vary the preestablishedeffective cross sectional area of said discharge orifice means affordingmaximum communication for the flow of liquid fuel between the interiorof said tubular bar and said conduit when said movable element is in itsfully open position.
 6. A fuel-to-air ratio regulating means as setforth in claim 5, wherein said discharge orifice means is partiallydefined by an elongated slit formed through the wall of said tubularbar, the longitudinal axis of said slit being substantially parallel tothe longitudinal axis of said tubular bar, said movable element includesa plunger mounted within said tubular bar for sliding movement along thelongitudinal axis of said tubular bar.
 7. A fuel-to-air ratio regulatingmeans as set forth in claim 4, further including manually operableadjustment means for said stop means, said adjustment means beingoperable to selectively vary the position of said abutment along thepath of movement of said plunger with respect to said slit.
 8. Afuel-to-air ratio regulating means as set forth in claim 7, wherein saidmanually operable adjustment means includes a rotatable cam having a camsurface formed thereon, and a cam follower operatively engaging said camsurface and connected to said abutment for cojoint movement along anaxis coincident with the movement axis of said plunger, said cam and camfollower being effective upon rotation of said cam to vary the positionof said abutment along the path of movement of said plunger with respectto said slit.
 9. A fuel-to-air ratio regulating means as set forth inclaim 8, further including remote control means for rotating said camremotely of the carburetor.
 10. A fuel-to-air ratio regulating means asset forth in claim 1, further including a liquid fuel reservoir;passageway means extending between and providing fluid communicationbetween said fuel reservoir and said tubular bar; and a fluidic deviceformed within a section of said passageway means between said fuelreservoir and said tubular bar, said fluidic device being responsive tothe absolute pressure magnitudes existing in certain regions of saidconduit spaced along the longitudinal axis thereof and being effectiveto control the fuel flow rate through said passageway means.
 11. Afuel-to-air ratio regulating means as set forth in claim 10, whereinsaid air-fuel conduit is formed with a reduced-diameter venturi portionupstream of said throttle valve and said fluidic device is disposedwithin said conduit at said venturi portion, said fluidic deviceincluding a wall section of said passageway means partially defining aninteraction zone, said fluidic device including a restricted fuel inletnozzle providing fluid communication between said fuel reservoir andsaid interaction zone, a signal pressure port for subjecting saidinteraction zone to the absolute pressure magnitude existing in saidconduit at said venturi portion, and an outlet port; said fuel reservoirbeing subjected to the absolute pressure magnitude existing in saidair-fuel conduit upstream of said venturi portion.
 12. A fuel-to-airratio regulating means as set forth in claim 11, wherein said fluidicdevice is vertically spaced above said tubular bar, and said passagewaymeans extending between said fluidic device and said tubular bar beingcapable of serving as means for storing fuel trapped when said movableelement is moved to its closed position